Methods and apparatuses intended to cut or produce lines of perforations in a moving target web are well known in the art. Conventional processes and machines have included a rotary knife roll and a stationary anvil. The rotary knife rolls have included removable and replaceable knife blades, which have extended generally along the axial direction of the knife roll, and have been distributed along the circumference of the knife roll with regular or irregular, intermittent spacing. In addition, the knife blades have been placed at an angle relative to the rotational axis of the knife roll. The placing of the blades on the roll at an angle has helped to reduce the impact loads generated during the cutting of the target web. In particular arrangements, it has also been necessary to skew the axis of rotation of the knife roll relative to the direction of the web movement past the knife roll. The amount of skewing has been suitably adjusted to obtain substantially straight cuts along the transverse cross-direction of the target web. Conventional techniques and devices are well known in the art, and suitable anvils and rotary knife rolls are available from commercial vendors.
Ordinary methods and apparatuses, however, have not provided desired combinations of efficiency and versatility, particularly when the cutting processes are operated with high web speeds. When conventional processes and machines have been arranged to cut a target web that is moving at high speeds past the anvil, the impact forces between the blade and the anvil have caused high rates of wear requiring frequent changing of the knife and anvil blades. To reduce wear, the amount of interference between the knife and anvil blades has been set to relatively small values. The small values of interference help to reduce wear, but can lead to areas of missing perforations in the web, due to vibrations in the components of the equipment and variations in the setup of the equipment. A poor quality in the perforations is not only poorly received by the final consumer using the product, but can also lead to a poor operation of the manufacturing process. For example, an individual perforation line is typically used as the separation line between rolls of finished product; and a poor quality perforation line can disrupt the reliability and quality of the separation process. It has also been cumbersome and time-consuming to reconfigure conventional systems to produce different spacing between the desired cut locations along the lengthwise movement direction of the target web. As a result, there has been a continued need for improved cutting systems that provide improved reliability and versatility, along with an improved and more reliable definition of the perforation line.